\documentclass[tikz]{standalone}
%\usepackage{tikz}
\begin{document}
\begin{tikzpicture}[circuit ee IEC, set resistor graphic=var resistor IEC graphic] 
   \pgfmathsetmacro{\rec}{1}
   \pgfmathsetmacro{\shifty}{1}
   \pgfmathsetmacro{\shiftx}{2.5}

%draw left part
\draw (0,0) --++(0,\shifty) %to [contact]+(0,0)
 +(-\rec,0) rectangle +(\rec,\rec) 
++(0,\rec) 
%to [contact]+(0,0) 
-- ++(0,\shifty);

\draw (0,0) to [resistor={info={$R_{a_{12}}$}}] ++(\shiftx,0) -- ++(0,\shifty)
 +(-\rec,0) rectangle +(\rec,\rec)
 ++(0,\rec) -- ++(0,\shifty);

\draw (\shiftx,0) to [resistor={info={$R_{a_{22}}$}}] ++(\shiftx,0)
to [contact]++(0,0) -- ++(0,\shifty)
 +(-\rec,0) rectangle +(\rec,\rec)
 ++(0,\rec) -- ++(0,\shifty) 
to [contact] +(0,0);

%draw right part
\draw (3*\shiftx,0) to [contact] ++(0,0) -- ++(0,\shifty)
 +(-\rec,0) rectangle +(\rec,\rec) 
++(0,\rec)-- ++(0,\shifty)
to [contact] +(0,0);

\draw (3*\shiftx,0) to [resistor={info={$R_{a_{22}}$}}] ++(\shiftx,0) -- ++(0,\shifty) +(-\rec,0) rectangle +(\rec,\rec)
 ++(0,\rec) -- ++(0,\shifty);

\draw (4*\shiftx,0) to [resistor={info={$R_{a_{23}}$}}] ++(\shiftx,0) -- ++(0,\shifty)
 +(-\rec,0) rectangle +(\rec,\rec)
 ++(0,\rec) -- ++(0,\shifty);


\draw (0,2*\shifty+\rec) -- ++(2*\shiftx,0);
\draw (3*\shiftx,2*\shifty+\rec) -- ++(2*\shiftx,0);


\node [contact] at (2*\shiftx+0.8,0){};
\node [contact] at (2*\shiftx+1.25,0){};
\node [contact] at (2*\shiftx+1.7,0){};
\node [contact] at (2*\shiftx+0.8,2*\shifty+\rec){};
\node [contact] at (2*\shiftx+1.25,2*\shifty+\rec){};
\node [contact] at (2*\shiftx+1.7,2*\shifty+\rec){};

% node[pos=0,draw,contact]{}
% node[pos=0.5,draw,contact]{}
% node[pos=1,draw,contact]{};


\node at (0,\shifty+\rec/2){soma};
\node at (\shiftx,\shifty+\rec/2){$\mathrm{dendrite_1}$};
\node at (2*\shiftx,\shifty+\rec/2){$\mathrm{dendrite_2}$};
\node at (3*\shiftx,\shifty+\rec/2){$\mathrm{dendrite_{14}}$};
\node at (4*\shiftx,\shifty+\rec/2){$\mathrm{dendrite_{15}}$};
\node at (5*\shiftx,\shifty+\rec/2){spine};

\node at (2.5*\shiftx, -0.5){Intracellular (Cytosol)};
\node at (2.5*\shiftx, 2*\shifty+\rec+0.5){Extracellular};

%current
\node ()[circle, draw, inner sep=2pt] at (0.5, 2*\shifty+\rec+1){};
\draw (0.5, 2*\shifty+\rec+1) to [current source]++(0,-1) 
to [contact]+(0,0);
\end{tikzpicture}
\end{document}